Solar mounting systems, designed for supporting varying numbers of solar panels with photovoltaic cells, are being installed as an alternative source of energy in many different settings, including smaller residential assemblies and larger commercial or utility assemblies. Especially in the context of larger solar mounting systems containing hundreds or thousands of solar panels at a single installation site, it is desirable to simplify the process and cost of installing the solar panels onto the support structures that maintain the solar panels raised above a base surface such as a roof or ground. Each separate step that must be performed to reliably connect and mount a solar panel onto the support structure must be repeated hundreds or thousands of times in this context, which results in significant additional hours of labor needed during installation for any additional steps that become necessary when mounting each solar panel. Therefore, the designers of solar mounting systems continue to endeavor for quicker and simpler installation techniques that still adequately provide the structural support and electrical bonding and/or grounding connections required for each of the solar panels.
In one example, each of the solar panels on a solar mounting system must be electrically bonded and/or grounded at conductive portions of the solar panels, such as the panel frames. For safety purposes, any conductive portion of the solar panels should be bonded or connected to an electrically conductive path configured to safely conduct any electrical current in the conductive portions to ground potential and away from the sensitive photovoltaic cells and other energy-producing equipment on the solar mounting system. However, the grounding of panel frames in solar mounting systems is made difficult by other design considerations necessary for solar mounting systems, such as the need to protect the conductive portion of the panel frames from harsh environmental conditions that may lead to corrosion and deterioration of the panel frames. As a result of this latter design consideration, panel frames formed from aluminum or a similar metallic material may be anodized and/or coated to provide a protective coating, which may be electrically insulative, to resist environmental conditions and corrosion. For anodized aluminum, the anodizing process effectively coats the outer surface of the aluminum electrolytically with a protective or decorative oxide that tends to protect the remainder of the aluminum material from environmental effects. But this protective coating makes it difficult to readily form an electrical bonding and/or grounding connection with the conductive portion of the panel frames, which is required when grounding solar panels.
One common practice to overcome this difficulty includes installing a separate grounding lug on each panel frame or piece that is coated or anodized. The grounding lug is typically attached to the panel frame via a thread forming stainless steel screw, which produces an air-tight connection when fastened to the panel frame. The stainless steel screw then optionally contacts a star washer in contact with a grounding lug frame, or contacts the grounding lug frame directly. A copper wire is captured by the grounding lug frame and runs through a plurality of the grounding lugs such that a common conductive path is defined from the panel frames, through the respective ground lug frames, and into the copper wire, which leads to ground potential.
Another example of a known grounding lug is shown in U.S. Patent Publication No. 2012/0125408 to Reyes et al., which illustrates the grounding lug as a separate piece that must be attached to each solar panel. Both of these grounding lugs require multiple connections between the parts described above to reliably form the electrical bonding path between the copper wire and the panel frame, and the installation of these grounding lugs is time-consuming and complex. The additional wiring of the copper wire to each of the grounding lugs also adds additional time and expense that multiplies exponentially when producing a large solar mounting system.
To avoid the need for the separate copper wiring, another typical practice is to insert star washers or similar members between the panel frames and the support structure to form an electrical bonding connection. A star washer is formed from flat metal stock so as to include a number of internal and/or external teeth that are twisted from the plane defined by the body of the star washer. These teeth tend to cut or dig into surfaces that the star washer abuts when the star washer is tightened between two adjacent components, such as the solar panel frame and the underlying support structure. In this regard, the twisted or bent teeth in the star washer may provide a constant spring force resisting deformation back to a planar form. The use of star washers might avoid the need to provide wiring through a plurality of grounding lugs. For a typical solar panel, this may include up to four fasteners that should be provided with the additional star washer part. One example of solar panel mounting using star washers for grounding is shown in U.S. Pat. No. 7,971,398 to Tweedie.
The accurate alignment and insertion of these star washers for each solar panel increases the complexity and cost of manufacturing larger solar mounting systems. Furthermore, the star washers must be carefully selected and tailored to reliably cut through the electrically insulative coating on the panel frames being used. For example, if the star washers are not formed strong enough for the teeth to resist the compressive forces on the solar panel and the supporting structure, the teeth may bend in some washers back to a planar state with the washer body, which causes a lack of electrical contact between the panel frame and the support structure. Numerous efforts have been made to address these concerns with star washers, including thickening the star washer and/or using a modified bonding washer commercially referred to as a WEEB, both of which are described in U.S. Pat. No. 8,092,129 to Wiley et al. In other systems, different types of structures have been used in place of star washers, such as the grounding clips shown in U.S. Patent Publication No. 2012/0097816 to Tamm et al., and the grounding clamps shown in U.S. Pat. No. 8,181,926 to Magno, Jr., et al.
However, each of these alternatives to star washers still requires additional installation work and cost to add these separate grounding components during the construction of a solar mounting system. Even if several of these alternative grounding components function better or are installed more rapidly than a grounding lug or a star washer, there are still additional costs associated with providing these grounding components for each solar panel and then installing these grounding components. For example, a star washer that may cost a few cents or a modified bonding washer that may cost a bit more are minimal in costs by themselves, but these parts are required for each connection made to the solar panels, and this incremental cost aggregates into a significant added expense for larger assemblies.
There is a need, therefore, for a solar mounting system and methods that further simplify the grounding process for each solar panel, thereby minimizing installation costs and improving the solar mounting system.